The invention discloses a gray 
brick mechanically manufactured from 
lime sludge and construction wastes and a method for manufacturing the same. The materials for mechanically manufacturing the gray 
brick comprise the following raw materials in portion by weight: 1,015 to 1,135 portions of 
construction waste crushed materials, 240 to 290 portions of 
cement, 810 to 1,010 portions of 
lime sludge, 60 to 75 portions of gray 
lime, and 100 to 125 portions of water, wherein the particle size of the 
construction waste crushed materials is less than 15 millimeters. If necessary, less than 20 portions of 
fly ash and proper amount of activating agent can be added to the materials. The method for mechanically manufacturing gray 
brick comprises the following steps: firstly, crushing the construction wastes; secondly, mixing the 
construction waste crushed materials with the other materials according to the proportions; and thirdly, pressing the mixture by adopting a mechanical method so as to produce the gray brick of the invention. The gray brick and the method for manufacturing the same recycle the 
sludge and the construction wastes in a reducing, harmless and resource-utilizing mode, and solve the problem that substituting materials and products are hard to find after clay bricks are forbidden to use and the problem of gray brick sources for civilian constructions.